This invention relates to a throttle opening limiting system for a marine propulsion unit, and particularly for watercraft outboard, as well as inboard-outboard, motors.
It has been known to provide a throttle opening limiting means in conjunction with a forward, neutral and reverse transmission system as a part of a watercraft propulsion unit. Such limiting means are operable to allow full opening of the engine throttle when the transmission is employed in the forward operating state, and to limit the throttle to an intermediate opening when the transmission is employed in the neutral or reverse operating states. Thus, overspeed rotation of the engine due to a fully opened throttle when the transmission is shifted into the neutral or reverse operating states may be avoided.
A problem with such throttle limiting systems exists, however, due to the fact that the maximum throttle openings for the neutral and reverse operative states have been set equal to one another. Thus, overspeed engine rotation cannot be prevented in the neutral operative state when the maximum throttle opening necessary for securing the proper thrust required for reverse running is employed. On the other hand, the maximum throttle opening necessary for preventing overspeed engine rotation in the neutral operative state cannot provide the necessary thrust required for proper running of the craft in the reverse operative state.
It is, therefore, a principal object of this invention to provide an improved throttle opening limiting system for a marine propulsion unit.
It is further an object of this invention to provide a throttle opening limiting system capable of preventing overspeed engine rotation in both the neutral and reverse transmission operative states, while nevertheless securing the necessary thrust required for proper running of the craft in the reverse operative state.